1. Field of the Invention
The field of art to which this invention pertains is hydrocarbon processing. It particularly relates to the recovery of desired liquid and vaporous constituents from a hydrocarbonaceous liquid-vapor feed stream. Specifically, this invention relates to the recovery of LPG and stabilized gasoline in an improved separation process.
2. Prior Art
Hydrocarbons which are vaporous at normal conditions are employed in the synthesis of many organic compounds. Ethylene, for example, is in demand as a starting material in the synthesis of alcohols and synthetic rubber. Propylene and butylenes are in particularly great demand for plastics manufacture and for conversion to high octane motor fuel blending components by polymerization and alkylation processes.
Sources of these vaporous hydrocarbons are petroleum cracking and conversion processes such as thermal cracking, catalytic cracking, reforming, hydrocracking, etc. The chemical reactions occurring in these processes produce commercially desirable quantities of vaporous hydrocarbons, and because of their utility it is desirable to recover them in as high a concentration as possible. For this reason, separation processes are commonly used to concentrate and recover these hydrocarbons.
Prior art separation processes, such as that described in U.S. Pat. No. 2,181,302, are comprised of three major sections or zones: absorption, stripping and fractionation. In essence, these zones serve, respectively, to absorb all but the lightest gaseous components, strip dissolved gases from the absorbed components, and fractionate the absorbed components into various product streams. An outstanding feature of these processes is that usually the heavier components in the feed to the process are suitable for use as an absorber oil in the absorption zone. A portion of the product stream containing these components is recycled back to the absorption zone. I have discovered an improvement which significantly improves the efficiency of such hydrocarbon separation processes.